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6.2 G) Pie Chart – Part 2
6.2 G) Pie Chart – Part 2
We are now going to have a look at finding values from a pie chart.
Example 1
There is an election in a town. There are 4 political parties to vote for; Conservative, Labour, Liberal Democrats and the Green Party. 4650 people voted for Labour.
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There is an election in a town. There are 4 political parties to vote for; Conservative, Labour, Liberal Democrats and the Green Party. 4650 people voted for Labour.
- How many people voted in total?
- How many people voted for each of the other parties (Conservative, Green Party and Liberal Democrats)?
Click here for a printable version of this diagram.
Part 1
The first part of the question asks us to work out the total number of people that voted in the election. We are told in the question that 4650 people voted for the Labour party and from this information, we can create an equation whereby the angle for Labour in the pie chart is equal to the number of people who voted for the Labour party. From this equation, we can find what 1° represents and then what 360° (which is the full circle) represents.
The first step creating the equation is to measure the angle for labour in the pie chart. The angle for labour is 155°.
The first part of the question asks us to work out the total number of people that voted in the election. We are told in the question that 4650 people voted for the Labour party and from this information, we can create an equation whereby the angle for Labour in the pie chart is equal to the number of people who voted for the Labour party. From this equation, we can find what 1° represents and then what 360° (which is the full circle) represents.
The first step creating the equation is to measure the angle for labour in the pie chart. The angle for labour is 155°.
This means that 155° is equal to the number of people who voted Labour (4650). Therefore, we can create the following equation.
We now need to find how many people 1° represents and we are able to do this by dividing both sides of the equation by 155°.
The total number of people who voted in the election will be what 360° represents. Therefore, we need to multiply both sides of the equation by 360.
Therefore, 10,800 people voted in the election.
Part 2
We now need to work out how many individuals voted for the other 3 parties. We do this by multiplying the degrees in the pie that represent that particular party by the number of people that 1° represents (30 people). The degrees for each of the parties are shown on the pie chart below.
Part 2
We now need to work out how many individuals voted for the other 3 parties. We do this by multiplying the degrees in the pie that represent that particular party by the number of people that 1° represents (30 people). The degrees for each of the parties are shown on the pie chart below.
We are now able to work out the number of people who voted for each party.
Conservatives
The degrees in the pie chart that represents the Conservative Party is 130°.
Conservatives
The degrees in the pie chart that represents the Conservative Party is 130°.
3,900 people voted for the Conservative Party.
Green Party
The degrees in the pie chart that represents the Green Party is 25°.
Green Party
The degrees in the pie chart that represents the Green Party is 25°.
900 people voted for the Green Party.
Liberal Democrats
The degrees in the pie chart that represents the Liberal Democrats is 50°.
Liberal Democrats
The degrees in the pie chart that represents the Liberal Democrats is 50°.
1,500 people voted for the Liberal Democrats.
A good final check for this question is to make sure that the number of people that voted for each party adds up to the same value as the value that we worked out for the total number of individuals that voted. In the first part of the question, we said that 10,800 people voted. When we add the number of individuals that voted for each individual party, we obtain the same number of people, meaning that we are probably correct (4,650 + 3,900 + 750 + 1,500).
A good final check for this question is to make sure that the number of people that voted for each party adds up to the same value as the value that we worked out for the total number of individuals that voted. In the first part of the question, we said that 10,800 people voted. When we add the number of individuals that voted for each individual party, we obtain the same number of people, meaning that we are probably correct (4,650 + 3,900 + 750 + 1,500).